1. Field of the Invention
This invention relates to an electronic controlled fuel injection system for use in an internal combustion engine and, more particularly, to a system including a fuel-injection timing control device for determining an optimum fuel-injection timing based upon various conditions of the engine that are sensed during its operation.
2. Description of the Prior Art
Fuel-injection timing control devices have already proposed which include a computer responsive to various engine operating conditions for determining an optimum fuel-injection timing so as to simultaneously satisfy high fuel economy, low engine noise, and low exhaust gas emission requirements. However, it is often required that the low engine noise requirement has priority over the high fuel economy requirement, for example, when the vehicle is garaged at night. The engine noise can be reduced to some extent by retarding the fuel-injection timing after the engine is warmed up.
The present invention provides a fuel-injection timing control system including control means manually operable for retarding the fuel-injection timing a predetermined value from the optimum fuel-injection timing value determined based upon various engine operating conditions.